US Bridges

Castle Shannon Blv over Saw Mill Run

Fair

Allegheny County, Pennsylvania · 300 NW of SR 88 · Structure no. 000000000001762

Built
1900
125 years old, rebuilt 1920
Condition
Fair
inspected March 2023
Type
Arch - Deck
Masonry
Length
23 ft
1 main span
Daily traffic
13,866
2024 count
Owner
State
State Highway Agency

About this bridge

Castle Shannon Blv over Saw Mill Run is a masonry arch - deck carrying Castle Shannon Blv over Saw Mill Run in Allegheny County, Pennsylvania. It was built in 1900 and reconstructed in 1920, so it is 125 years old, older than the Pennsylvania average of 54.8 years.

The most recent inspection reported to the Federal Highway Administration rates it in fair condition with a lowest component rating of 5 out of 9. The lowest-rated primary component is rated 5 or 6. Minor deterioration is present but the structure is sound.

It carries about 13,866 vehicles a day, roughly 3% of them trucks, projected to reach 16,208 by 2032. The structure is 23 ft (7 m) long and 45 ft wide. If it were closed, the detour would be 3.1 mi (5 km).

Location

Open in Google Maps
CarriesCastle Shannon Blv
CrossesSaw Mill Run
Location300 NW of SR 88
RouteState Highway 0
CountyAllegheny County
StatePennsylvania
Coordinates40.36514, -80.02382
Functional classUrban Minor Arterial

Condition and inspection

Fair

The lowest-rated primary component is rated 5 or 6. Minor deterioration is present but the structure is sound.

ComponentRatingMeaning
Superstructure5 FairAll primary structural elements are sound but may have minor section loss, cracking, spalling or scour.
Substructure5 FairAll primary structural elements are sound but may have minor section loss, cracking, spalling or scour.
Channel and channel protection4 PoorAdvanced section loss, deterioration, spalling or scour.
Last inspectionMarch 2023
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourFoundations stable; action required to protect exposed foundations
Structural evaluation5: Somewhat better than minimum adequacy to tolerate being left in place as is
Deck geometry2: Basically intolerable, requiring high priority of replacement
Waterway adequacy9: Superior to present desirable criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating80 US tons
Inventory rating48 US tons

Structure

Structure typeArch - Deck
MaterialMasonry
DeckNot applicable
Main spans1
Design loadHS 20
Structure length23 ft (7 m)
Longest span18 ft (5.5 m)
Deck width45 ft (13.7 m)
Roadway width27 ft (8.2 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic13,866 (2024)
Projected traffic16,208 by 2032
Trucks3%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway
CrossesWaterway
Detour if closed3.1 mi (5 km)
TollOn a free road
National Highway SystemYes

Ownership and planned work

OwnerState Highway Agency
Maintained byState Highway Agency
Historic statusNot eligible for the National Register of Historic Places
Work proposedRehabilitation because of general structure deterioration or inadequate strength
Estimated improvement cost$71,000
NavigationNo navigation control on waterway

Frequently asked questions

When was Castle Shannon Blv over Saw Mill Run built?

It was built in 1900, making it 125 years old in 2025. It was reconstructed in 1920.

What condition is Castle Shannon Blv over Saw Mill Run in?

The National Bridge Inventory rates it in fair condition. The lowest-rated primary component is rated 5 or 6. Minor deterioration is present but the structure is sound. The last reported inspection was in March 2023.

How much traffic does Castle Shannon Blv over Saw Mill Run carry?

About 13,866 vehicles per day (2024 count), of which roughly 3% are trucks.

How long is Castle Shannon Blv over Saw Mill Run?

The structure is 23 ft (7 m) long with a longest span of 18 ft (5.5 m) and a deck 45 ft wide.

Who owns Castle Shannon Blv over Saw Mill Run?

It is owned by the State Highway Agency.